M14 Forum

USMC 711 · January 21st, 2012, 02:57 PM

Does anyone bother to re-crown chrome barrels, or, does the flash suppressor govern the accuracy?

RAMMAC · January 21st, 2012, 03:32 PM

I'm not a gunsmith so don't take my comments as being from one, but I've read that some people don't recommend re-crowning a chrome lined barrel because you can create chips in the chrome and that would worsen your accuracy. The finish of the muzzle will always have an effect on precision and accuracy but the fit of the flash suppressor will also be of importance. Anything that causes there to be uneven pressure on the bullet as it leaves the muzzle will not help your groups.

If it were my rifle, I would clean up any marks on the face of the muzzle with a stone. As for the crown, some gunsmiths and some bench rest shooters no longer recommend any crowning at all, they claim that crowning was just a way to avoid damage to the lands and groves at the muzzle and since there is a flash suppressor on the muzzle the front faces of the exposed lands are protected, so I wouldn't worry too much about the crown unless the actual angled face has dings in it. The next thing I would do is ensure that the flash suppressor fits against the muzzle with no gap between the two, of course I would also ensure that it's straight and inline with the axis of the bore.

Lazerus2000 · January 21st, 2012, 03:45 PM

I've seen an awful lot of 22" chrome lined M14 barrels that had dinged up crowns, and re-crowning might save you $$$ for a replacement barrel. Just check the throat erosion and muzzle erosion before wasting too much time working on a questionable barrel.

I've done about 100 or so M14 shorties, most with chrome lined barrels. Cutting 3" off the muzzle is one way to get rid off bad muzzle erosion, most likely caused by rought cleaning with the steel 14 cleaning rod, than by the actual number of rounds fired down range. The M14 flash hider is NOT really a very good cleaning rod guide ... use a shotgun shell drilled out at the primer over the flash hider if you are fussy about crown wear.

When you cut an M14 barrel for a shorty, the chrome CAN flake, so we usually cut a bit long with an ordinary hack saw, chuck the barrel in a lathe, and using a carbide tool, work back to the length we want. I like 18 3/4" barrels for my shorty 14s, which makes them 1/4" longer than the Canadian legal length of 18.5". That extra 1/4" is cheap insurance ...
I've only seen a couple of crown jobs where the chrome flaked during the finishing, and needed to be redone, but better safe than sorry.

PS: crowning is always done cutting from the inside out, so you are pressing the chrome INTO the barrel metal rather than FLAKING IT OFF into the air in the bore.

Good luck with that ...
[;)
LAZ 1

adrbe · January 21st, 2012, 04:10 PM

Dave Manson makes a crowning tool, with carbide cutters, that he says can be used to recrown chrome lined barrels.

Take a look at this video:

http://www.youtube.com/watch?v=b23lfzpZrJ4

honer · January 21st, 2012, 04:32 PM

I antied up and purchased Mansons crowning tool a couple of years ago. It has more than paid for itself especially in those jobs where, for one reason or another, you don't want to remove the barrel. It has replaceable carbide cutters and is designed very well IMHO. It's very quick and cuts a nice crown. I'm not connected with Manson other than being a customer.

Honer

USMC 711 · January 21st, 2012, 06:53 PM

Very thoughtful replies. Thank you all.

711

nf1e@snet.net · January 22nd, 2012, 03:26 AM

Been using the ball end of the cleaning rod from a combo tool in an electric drill for years. A little lapping compound and you can touch up the crown in no time.
Semper Fi
Sgt USMC 66-72 RVN 67-68

bd111 · January 22nd, 2012, 04:51 AM

If the crown's dinged enough to affect the end of rifling, or - especially and more commonly - if the face of the muzzle isn't square, seems to me a waste of time & ammo to use the barrel without fixing it. If you're careful to get securely chucked and leveled, I don't see how facing or a kiss to the crown with a diamond-impregnated ballstone is going to disturb the chrome lining unless the barrel's already shot out.

Rojkoh · January 26th, 2012, 02:48 AM

Quote:

Originally Posted by USMC 711

Does anyone bother to re-crown chrome barrels, or, does the flash suppressor govern the accuracy?

Are you talking about the USGI chrome lined barrels? Those are the only "Chrome" barrels made for the M14/M1As built afterwards.

Whew I don't even want to think about all the M14 barrels I've seen and had. I've got two Kreigers Stainless barrels out in the shop right now. Yes, a M14/M1A barrel is crowned. Shouldn't need to be recrowned. More typically it needs a new barrel, something you can check with a throat erosion gauge from Brownells.com, M1/M14/M1A Throat Erosion Gauge: #022-101-030 $ 62.50

The flash suppressor itself is reamed out with an NR #7 standard taper reamer to clear it of any interference. I forget which of the developer's came up with this (have to go to my notes on this one), but he found that if X number of raindrops collected in the suppressor, the bullet would come apart. I know, I learned the hard way in the snow when I dropped 2 shots at a match. Couldn't figure it out until the lead engineer at TRW for the 14 production told me about it, and handed me the USMTU guidelines for the M14 NM.

USMC 711 · January 26th, 2012, 03:31 AM

Actually I was concerned with a small amount of carbon on the crown face of a slightly used criterion barrel, which I since cleaned off with a stone.

Any I have thought about those flash suppressors - would be a great idea to have someone run the correct drill bit through one to bring to NM standards, nothing too complicated I would hope.

Thank you.

711

tmcfalls · January 26th, 2012, 05:29 AM

Quote:

Originally Posted by Rojkoh

Are you talking about the USGI chrome lined barrels? Those are the only "Chrome" barrels made for the M14/M1As built afterwards.

Whew I don't even want to think about all the M14 barrels I've seen and had. I've got two Kreigers Stainless barrels out in the shop right now. Yes, a M14/M1A barrel is crowned. Shouldn't need to be recrowned. More typically it needs a new barrel, something you can check with a throat erosion gauge from Brownells.com, M1/M14/M1A Throat Erosion Gauge: #022-101-030 $ 62.50

The flash suppressor itself is reamed out with an NR #7 standard taper reamer to clear it of any interference. I forget which of the developer's came up with this (have to go to my notes on this one), but he found that if X number of raindrops collected in the suppressor, the bullet would come apart. I know, I learned the hard way in the snow when I dropped 2 shots at a match. Couldn't figure it out until the lead engineer at TRW for the 14 production told me about it, and handed me the USMTU guidelines for the M14 NM.

For a person who touts himself as an M14 expert you seem to be missing a lot of recent and relevant knowledge.

http://lrbarms.com/m14parts.html

Look at the 3rd barrel down on the list.

Ted Brown · January 27th, 2012, 11:46 AM

The important thing to keep in mind is that the barrel of the M14 must mate against the inside of the flash suppressor. The muzzle of the barrel must be absolutely square as should the matting FS surface. If there is damage to the barrel crown it needs to be squared as well as camfered into the rifling. This can be done using a lathe or tools specifically made for the purpose. The proper GI tools are 7799721 for facing the muzzle and flash suppressor, and 7799719 for cutting the bevel in the crown. I realize that few are going to have these tools, but suitable substitutes are available from Brownell's. The military tools are carbide and are compatible with chrome lined barrels, but I am not sure about commercial sustitutes.